Half of patients with insulin-dependent diabetes mellitus develop renal failure after 28 or more years. Effective blood pressure control slows the progression of established diabetic nephropathy. Recent evidence strongly suggests that angiotensin converting enzyme inhibitors reduce the level of proteinuria in early diabetic nephropathy, and slow the progression of renal disease in these patients. The Collaborative Study of ACE-inhibition and Diabetic Nephropathy have recently completed a randomized clinical trail of captopril vs. Placebo in adults with insulin-dependent diabetes and early diabetic nephropathy. After an average of four years of follow-up, there was a clear reduction in the rate of progression of renal failure in subjects randomized to captopril therapy compared to those randomized to placebo. The Collaborative Group seeks now to establish the optimal blood pressure goal for Type I diabetics with early nephropathy who are treated with ACE-inhibitors. Thus, the purpose of this study is to determine the optimal level of blood pressure control in patients with Type I diabetic nephropathy. This is a randomized controlled trial in which subjects with early diabetic nephropathy receive angiotensin-converting enzyme therapy (Ramipril), and are randomized to one of two blood pressure goals, either usual blood pressure control or "strict" blood pressure control. The outcome variable is glomerular filtration rate. Subjects are admitted to the Clinical Research Unit periodically for I125-iothalamate clearance as an accurate measure of glomerular filtration rate (kidney function). This is measured every 8 months for 2 years. In the past year there were 16 measurements made. This study will continue through the next year.